As infusion pumps employed to infuse medical drug solution into a patient's body, various types of infusion pumps are known, including mechanical infusion pumps, gravity infusion pumps which entirely depend on gravity, and precompression-type infusion pumps.
Mechanical infusion pumps include syringe infusion pumps in which a piston of a syringe is pressed to feed infusion liquid, and peristaltic infusion pumps. Peristaltic infusion pumps include roller infusion pumps in which an infusion tube is pressed by a roller-equipped rotor or the like to feed infusion liquid, and finger infusion pumps.
Among these infusion pumps, a peristaltic finger infusion pump is equipped with a pump mechanism having, for example, a plurality of fingers aligned in one direction (along an infusion tube), cams for advancing and retracting the fingers independently, a door of the pump, and a pressing plate provided on the door in a manner opposed to tips of the fingers while the door is closed. With an infusion tube being connected to an infusion bag and attached between the plurality of fingers and the pressing plate, the cams cause the fingers to advance and retract independently. By such finger movements, the infusion tube is pressed successively by each of the fingers, so that infusion liquid is fed by a peristaltic action (see, for example, Patent Literature 1 and Patent Literature 2).
Infusion treatment using such an infusion pump poses a risk of “free flow”. Free flow, an incident that infusion liquid falls under gravity and is administered to a patient in an excessive amount, may occur when an infusion tube is removed from the infusion pump or in other occasions. A conventional anti-free flow safeguard is to block an infusion tube by a roller clamp. A specific example of this safeguard is described below.
Generally, an infusion set for administering infusion liquid is composed of an infusion tube to be connected to an infusion bag, a drip chamber provided along the infusion tube, a roller clamp, a needle (an intravenous needle) connected to a patient's end of the infusion tube, and the like. A procedure for attaching the infusion tube of this infusion set to the infusion pump includes: blocking the infusion tube by the roller clamp, then attaching the infusion tube to a pump body (a pump mechanism unit) while the door of the infusion pump is kept open, and finally closing the door of the infusion pump. At this time (i.e. when the door is closed), at least one part of the infusion tube is blocked in the pump mechanism unit of the infusion pump. After the infusion tube is attached in this manner, a procedure for starting infusion treatment includes: releasing the roller clamp, and thereafter driving the infusion pump to start prescribed infusion treatment. A procedure after the finish of infusion treatment includes: stopping the infusion pump, then blocking the infusion tube by the roller clamp, opening the door of the infusion pump in this state (an anti-free flow state), and removing the infusion tube. These operational procedures can prevent free flow during preparation of infusion treatment and during removal of the infusion tube from the infusion pump.
As the examples of anti-free flow safeguards, Patent Literature 3 and Patent Literature 4 mentioned below disclose use of special clamps with an anti-free flow function.